A quick one today – some tips I employ when filling the car with petrol, which I’ve since researched (a bit) and have (a bit) of science to back them up! Much of the original wording comes from a forum post on this site, the author though sadly is uncredited, it was coincidence I happened to be following some of his tips.

Only fill up your vehicle in the early morning when the ground temperature is still cold. All service stations have their storage tanks buried below ground. The colder the ground the more dense the petrol, when it gets warmer petrol expands, so if buying in the afternoon or in the evening the litre rwecorded by the meter is not a true litre of fuel.

In the petroleum business, the specific gravity and the temperature of the petrol, diesel and jet fuel, ethanol and other petroleum products plays an important role. A 1-degree rise in temperature is a big deal for this business. But the service stations do not have temperature compensation at the pumps.

When you’re filling up you might notice that the pump hose trigger has two or even three settings: low, middle, and high. You should be pumping on the lowest (and therefore slowest) mode, thereby minimizing the vapours that are created while you are pumping. All hoses at the pump have a vapour return. If you are pumping on the fast rate, a greater portion of the liquid that goes to your tank becomes vapour. Those vapours are actually being sucked up and back into the underground storage whilst you’re pumping, but the dial on the pump doesn’t compensate for that so you’re getting less fuel for your money.

One of the most important tips is to fill up when your petrol tank drops no lower than HALF FULL. The reason for this is the more petrol you have in your tank the less air occupying its empty space. Petrol evaporates faster than you can imagine. Petrol storage tanks have an internal floating roof. This roof serves as zero clearance between the Petrol and the atmosphere, so it minimizes the evaporation.

Your car doesn’t have such an arrangement. I’m not sure of the science of this bit to be honest, my guess is the vapour isn’t drawn through to the cylinders unlike the liquid; but I can vouch for the practice from a practical point of view. By never letting your tank drop below half you always have options for when and where you fill up. We run this protocol (steady, Ed.) for both cars and found it got us through that nonsense a year ago when a tanker driver strike was talked about, and everybody panicked and emptied the forecourts of what fuel they did have. We had sufficient in reserve to be able to avoid all that madness.

Of course if you have a specific one-use only money-off voucher it makes sense to have as empty a tank as possible before you fill, but these should be the exception not the norm.

Another reminder, if there is a petrol truck pumping into the storage tanks when you stop to buy Petrol, DO NOT fill up; most likely the petrol is being stirred up as the Petrol is being delivered, and you might pick up some of the dirt that normally settles on the bottom. At best the fuel won’t burn efficiently enough in your cylinder heads, at worst the crap will start to block up and damage the bits of your engine it comes into contact with. Again if you run the ‘no-less-than-half’ protocol mentioned above, you can just drive on and find the next cheapest forecourt.

You can see how these tips work together, as if you go earlier in the morning on half-a-tank, you’re more likely to drive straight to the pump, there won’t be a tanker unloading at the same time and there will be less people waiting so you can top up with the densest fuel on the slowest setting.

I have somehow picked up some non-serious but weird medical condition that is beyond the expertise of my local or even regional health authority, and I have been referred up the food chain. Out of the blue a letter arrived in the post for an appointment at a hospital in London. Yes; London. Not scary for some people I know but for a country mouse like me living in the fields of North Shropshire, it might as well have been Sydney or New York. It was also for 9:30 in the morning…

There was talk of going down the night before and putting up in a hotel, but Marky is nothing if not a tight-wad, so Wednesday morning (5:45) saw me standing wide-eyed and fidgetty on Stafford station platform ready to catch the Red-eye to London Euston, weighed down with a knap-sac full of breakfast goodies, a lunch box, a flask of coffee and a good book.

I had a plan to make my way to the hospital, factoring in plenty of contingency time (I hate being late for anything, I find it the height of bad manners), and having pored over maps and timetables, deliberately chose the cheaper but earlier train – hence the owl-spooking 5am drive across the Shropshire-Staffordshire border.

Once off at Euston – man! that’s a huge station, it’s like an airport – I stood a bit desolate and lonely wondering what to do next – I still had 2 hours before the appointment. Being unfamilir with London’s rush hour I decided the best option was to get to the vicinity of the hospital first then see how I was doing for time. I went to the loo – uh oh, first mistake, that’ll be 30 pence please, that was why the lady sitting across the aisle from me on the train visited the loo on the carriage a couple of times before she got off – then got sucked into the heaving mass of people joinimng the underground.

Now despite knowing where I was going and walking in what I thought was a purposeful manner (I’m a tall bloke so even my leisurely pacing is fairly brisk) practically everybody else overtook me, all scurrying somewhere like busy worker ants. I had read that city living makes everyone move faster but it was eye-opening actually witnessing it. It was also a pleasure knowing I didn’t have to move at that speed everyday.

Any ways without further incident I was seen at the hospital fairly efficiently and with the delightful prospects of further appointments in the Metroplois in the next few weeks found myself back out on the pavement by 10 am. My return train wasn’t due to leave for another five hours so the whole city was mine for the taking.

I droped into a Costa coffee shop (I find the monotonous familiarity of chain coffee shops somehow reassuring, especially whenever I’m in a foreign city) to review my options and phone home, then decided to re-enter the underground and head up to Trafalgar Square and take a wander round the National Gallery – as it was free, and I didn’t have an eight-year-old in tow for once.

What it says on the sign – no idea who the girl is though..

I’d already scoped out its prospects on line before leaving for London, so knew it was a good place to while away somw free hours. It was a fantatsic couple of hours to be honest – I didn’t rush round and try and do all of it – it’s too big, but I could linger over those paintings that caught my eye, regardless of how famous (or not) they were. There were a surprising number of nudes and topless ladies on display in many of those paintings as well which is always a bonus.

Lunch was taken alfresco from Markys butty Box situated immediately outside the Gallery, in the weak February sunshine watching the street performers in the Square (I sat behind them; I could see them but they couldn’t really see me), while just down the road the Union Flag fluttered briskly above the mother of all Parliaments. It was all there – black cabs, red buses, Japanese tourists and pigeons; the lions, the fountains and above it all Lord Nelson standing defiantly in the wind.

It wasn’t that gloomy – I was shooting into the sun!!

I’d got myself to the centre of the craziest, liveliest city on the planet with absolutely no problem, and more importantly little expense (I figured that after transport costs I’d contributed less than a fiver to London’s coffers – sorry Boris!) and was actually enjoying being there. OK it had cost me a day’s annual leave, but I can always make that back thorugh working flexi.

All in all I felt pretty chuffed with myself and my self-reliancy.

I must do this again soon. Oh, wait a minute – the post has come and look! yes there it is. Another appointment – no two appointments. Looks like I’ll be back in a month’s time. I wonder how I can exploit my new-found skill in enjoying cheap day trips to London. Maybe I should start a website…